Bioactivity of umbilical cord blood dendritic cells and anti-leukemia effect

We investigated the effect of umbilical cord blood dendritic cells (DCs) on in vitro proliferation, immunophenotypes and levels of homologous cytokine-induced killer cells (CIK) and the toxicity on leukemia cells.

Mononuclear cell-induced DC-CIK cells derived from umbilical cord blood were collected and co-cultured in the proportion of 1:5. Cord blood CIK cells or peripheral blood DC-CIK cells were used as control. Phenotypes were analyzed by flow cytometry; vial cell counting was performed using trypan blue, and the killing activity of effector cells against leukemia cells was measured by MTT assay. The levels of interferon-r (IFN-r), tumor necrosis factor-a (TNF-α) and interleukin-12 (IL-12) were determined by ELISA.

The proliferative capacity of DC-CIK cells was obviously improved compared with cord blood CIK cells and peripheral blood DC-CIK cells (P<0.05, P<0.05). During the co-culture of cord blood DC-CIK cells, the ratios of CD 3 (+) CD 8 (+) and CD 3 (+) CD 56 (+) cells were obviously higher than that of CIK cells under the same conditions (P<0.05). On day 3 of co-culture, the levels of IL-12, IFN-r and TNF-a in cultured supernatant of cord blood DC-CIK cells were all higher than those secreted by CIK cells cultured alone (P<0.01, P<0.05, P<0.05). When the effector to target ratio was 2.5-20:1, the killing effect of cord blood DC-CIK cells against each subtype of acute leukemia cells was obviously higher than that of CIK cells (P<0.05). No significant differences in killing effect were observed for different subtypes. This finding was consistent with the killing effect of peripheral blood DC-CIK cells against leukemia cells.

Cord blood DCs can enhance the proliferative capacity of homologous CIK cells and its anti-leukemia effect. Though cord blood DC-CIK cells showed a higher proliferative capacity than peripheral blood DC-CIK cells, the two types of DC-CIK cells did not differ significantly in terms of cytoxicity. With a high availability and the low probability of graft rejection reaction, cord blood DC-CIK cells have a brighter prospect for application in immunotherapy.